In the field of microfabrication represented by the manufacture of integrated circuit devices, lithographic technology enabling microfabrication with a line width of about 200 nm or less using an ArF excimer laser (wavelength: 193 nm), F2 excimer laser (wavelength: 157 nm), and the like has been demanded in order to achieve higher integration in recent years. As a radiation-sensitive resin composition applicable to the excimer laser radiation, a number of chemically-amplified radiation-sensitive compositions utilizing a chemical amplification effect between a component having an acid-labile functional group and an acid generator, a component generating an acid upon irradiation, have been proposed.
As polymers that can be used for a radiation-sensitive resin composition, a (meth)acrylate polymer having a lactone structure (Japanese Patent No. 3042618 (Claims)), a compound having an alicyclic group with a specific structure, in which one of the carbon atoms forming the ring skeleton has a deprotecting group having a moiety substituted by a suitable lower alkyl group or in which the ring skeleton has a deprotecting group bonding by an ester bond via at least one atom other than the carbon atom (Japanese Patent Application Laid-open No. 9-73173 ([0137])), a chemically-amplified positive-tone resist composition comprising a resin possessing alkali-solubility protected by a 2-alkyl-2-adamantyl group or 1-adamantane-1-alkyladamantyl group, being insoluble or scarcely soluble in alkali by itself, but becoming alkali-soluble by the action of an acid, and a specific sulfonium salt acid generator (Japanese Patent Application Laid-open No. 2002-156750 ([0008])), a polymer for photo resist prepared by ternary copolymerization of a specific substrate-adhesive alicyclic ester, an acid-labile ester having a specific alicyclic skeleton, and, as a third component, a specific alicyclic ester having a polarity between the above first component and the second component (Japanese Patent Application Laid-open No. 2002-145955 ([0008] and [0009])), a resin which contains three types of monomer units of specific structures having an alicyclic skeleton at a specific rate (Japanese Patent Application Laid-open No. 2002-201232 ([0009] and [0010])), and the like have been known.
However, to achieve a higher degree of integration in the field of semiconductor, a radiation-sensitive resin composition used as a resist is required to possess more excellent resolution. To promote resolution and to produce more accurate pattern configuration, radiation-sensitive resin compositions with a variety of combinations are used. For example, different radiation-sensitive resin compositions are used for forming contact holes and for line-and-spaces. There may be a case where only one radiation-sensitive resin composition is used in order to shrink manufacturing process steps. A thermal flow technique to decrease contact hole pattern size by post baking after development is used to form contact holes with a small dimension. However, there are no radiation-sensitive resin composition using ArF excimer laser (wavelength: 193 nm), F2 excimer laser (wavelength: 157 nm), enabling microfabrication with a line width of about 200 nm or less using with thermal flow technique. Slight roughness produced during etching operation adversely affects resolution as the contact holes become small and lines-and-spaces become narrow.